Engineering thermoplastics and elastomeric materials are often used in numerous and diverse applications in order to produce molded parts and products. For instance, polyester polymers and polyester elastomers are used to produce all different types of molded products, such as injection molded products, blow molded products, and the like. Polyester polymers, for instance, can be formulated in order to be chemically resistant, to have excellent strength properties and, when formulating compositions containing polyester elastomers, to be flexible. Of particular advantage, polyester polymers can be melt processed due to their thermoplastic nature. In addition, polyester polymers can be recycled and reprocessed.
Although polyester polymers can be used in numerous applications, the materials do have some limitations. For example, problems have been experienced in the past in processing polyester polymers. For instance, some polyester polymers have relatively high viscosities or other flow properties that create problems when molding the polymers into different shapes. Polyester polymers, particularly polyester elastomers, for instance, can have low melt strength which causes issues during extrusion and blow molding. In addition, polyester polymers may darken or yellow in color over time and may produce a surface appearance that is less than desirable. For instance, many polyester polymers have a tendency to produce a dull surface. For example, a need currently exists for a polyester polymer composition having higher surface gloss characteristics in conjunction with higher strength characteristics.
In certain applications, thermoplastic polymers are combined with fibrous fillers in order to increase the modulus of parts and products made from the reinforced composition. Problems have also been experienced in the past in incorporating reinforcing fibers into a polyester polymer matrix that has the desired balance of properties. For instance, polyester polymer composites containing reinforcing fibers may have adequate strength properties but have relatively low elongation at break properties.
In view of the above, a need exists for polyester polymer compositions that can be formulated so as to have a desired balance of physical properties and characteristics.